Effect of TGF-β 1–triggered down-regulation of SDF-1 secretion in α 4β 1-dependent cell adhesion. BCECF-AM–labeled NCI-H929 (A) and Mo7e (B) cells were preincubated with anti-CXCR4 or anti-α 4 antibodies, T134, or adhesion medium alone and subsequently were exposed for 1 minute at 37°C to supernatants from MS-5 cells treated with or without TGF-β 1 (+ TGF-β 1 and –TGF-β 1, respectively). Cells were added to wells containing sVCAM-1 (i) or FN-H89 (ii) and were subjected to adhesion for 2 minutes after a short spin. To some adhesions, TGF-β 1 was added to the medium (MS-5 Sup/+ TGF-β 1). Nonbound cells were washed, and the extent of adhesion was measured in a fluorescence analyzer. Also shown is the triggering of cell adhesion by recombinant SDF-1α (100 ng/mL) compared with samples incubated with adhesion medium alone (control). Data represent the means ± SDs of triplicate samples from a representative result of 3 experiments for each cell type. Reduction in triggering of cell adhesion was significant (**P < .005; *P < .05), according to Student 2-tailed t test.